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rhkoncepts
Posts: 1
Registered: ‎09-11-2013

Applying beam offsets basics

218 Views, 1 Replies
09-12-2013 12:51 AM

Hi everyone,

 

I'm totally new to Autodesk Simulation 2013, but I've been driving Inventor for a good while.

Can anyone point me to a "click by click" idiot guide instruction of how to apply an offset to a rectangular hollow section that is attached side on to a 3mm sheet section? I have tried solidly for 2 days and am totally baffled so I must be missing a fundamental point. What mesh type should it be? I.e.. shell/plate - midplane etc? For hours it kept reverting to "brick" after I repeatedly change it to "beam". So a brief run down of how to setup a basic RHS type beam would also be helpful because I'm really not sure what iI changed to maintain its "beam" type.

I have defined the RHS cross section, which seems correct.

Sorry to be ignorant but I got to start somewhere.

 

Pete.

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Valued Mentor
AstroJohnPE
Posts: 503
Registered: ‎08-30-2012

Re: Applying beam offsets basics

09-12-2013 06:11 AM in reply to: rhkoncepts

Hi Pete,

 

This is just a guess based on your description, but I think you are confusing the name of the element type with the terminology of your structure. I agree that the RHS (something hollow section?) is referred to as a beam in common engineering language, but that does not imply that the simulation must use beam elements as the element type.

 

It sounds like you have created a solid model of the sheet and the RHS (stiffener beam), imported that into Simulation, and created a solid mesh. In other words, the CAD model includes the volume of all of the parts, and the simulation model also includes the volume of the parts. The only element type that corresponds to a volume mesh is a brick element (and its cousin, the tetrahedeon). You do not need to set that part to beam elements. You do not need to enter any "offset" because the model includes it already.

 

Just to elaborate a bit more without going into too much details, here are the different meshes and element types that could be used to represent a physical beam:

  • Brick elements. The mesh includes the entire volume of the parts. (Think of building the part from Legos. That is what a brick element mesh looks like.) 
  • Plate (or shell) elements. The mesh is the surface of the beam where the thickness of each portion is collapsed to 0 thickness. So a plate mesh of a length of pipe would look like a thin cardboard tube. The volume of the real beam is equal to the area of each plate element multiplied by the thickness of each element, where the thickness is a number entered into the Element Definition.
  • Beam elements. The mesh is a line located at the centroid of the real beam, and divided into short lengths; that is, the mesh. So the simulation model would look like a stick figure that one would draw of a beam structure. The volume of the real beam is equal to the length of each beam element multiplied by the cross-sectional area of each element, where the cross-sectional area is a number entered into the Element Definition.

If you have more questions, please attach an image of the model or mesh from Simulation.

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
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